Virtual Aids to Navigation

The new S-101 standard (which will eventually replace S-57) has defined a new object for Virtual AtoNs. Up till now, I had defined radio station category tags to encode these objects. Now that there is formally defined scheme for them, I have created a new object type together with its attributes. See: https://wiki.openstreetmap.org/wiki/Sea … tual_AtoNs

I have implemented this change in the renderer & the INT-1 JOSM preset. I have also updated the objects in the database to use these new tags.